Adhesive Film Composition for Foldable Optical Display Reliability
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Solution Overview
Problem
Flexible optical displays require adhesive films with good adhesive strength, foldability at various temperatures, and durability to maintain reliability and optical transparency, but existing films fail to meet these requirements, especially when held in a folded state for extended periods.
Innovation Solution
An adhesive film with specific tan δ ratios at 25° C. and −20° C., formed from a monomer mixture including hydroxyl group-containing (meth)acrylic acid esters, exhibits good foldability and mechanical properties, ensuring reliable adhesion and durability across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the adhesive film is held in a folded state for a long period of time to form a pleat, then the flexible display can be stored or transported in a compact form, but the adhesive film deteriorates in reliability, optical transparency, and durability
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive film by incorporating specific monomers (hydroxyl group-containing methacrylic acid ester, carboxyl group-containing methacrylic acid ester, and amino group-containing methacrylic acid ester) in controlled ratios. This chemical parameter change enables the adhesive film to maintain its functional properties even when folded for extended periods, resolving the contradiction between compact storage capability and long-term reliability.
2Strength
If the adhesive film is made with high adhesive strength to ensure good bonding between window film and conductive film, then the structural integrity is improved, but the foldability and flexibility are reduced
Solution Approach 1:
The patent achieves the balance between adhesive strength and foldability by precisely controlling the compositional parameters of the adhesive film. The specific ratio of functional monomers (hydroxyl, carboxyl, and amino group-containing methacrylic acid esters) creates an adhesive composition that provides strong bonding while maintaining flexibility, allowing the film to be folded without compromising either adhesion or bendability.
3Ease of operation
If the adhesive film is designed for good foldability at low temperature, then the flexible display can operate in cold environments, but the adhesive strength and mechanical properties may deteriorate
Solution Approach 1:
The patent addresses the temperature-dependent performance contradiction by selecting monomers with specific chemical structures that maintain their physical properties across a wide temperature range. The hydroxyl, carboxyl, and amino group-containing methacrylic acid esters are chosen for their ability to provide both flexibility at low temperatures and adequate adhesive strength, ensuring consistent performance in cold environments.
Data Source
AI summary
An adhesive film, an optical member including the same, and an optical display including the same are provided. An adhesive film has a tan δ ratio at 25° C. of about 1 to about 2 as calculated by Equation 1 and a tan δ ratio at −20° C. of about 0.1 to about 1.5 as calculated by Equation 2, and is formed of an adhesive composition including a monomer mixture including a hydroxyl group-containing (meth)acrylic acid ester.